1. Field of the Invention
The present invention relates to methods of manufacturing a multi-layer ceramic condenser, and more particularly, to a method of manufacturing a multi-layer ceramic condenser that forms an external electrode by forming through holes in a laminate of a plurality of ceramic dielectric sheets and filling the through holes with conductive paste.
2. Description of the Related Art
In general, condensers are passive components that apply a voltage and accumulate electric charges according to an electrode area with respect to a thickness of a dielectric material. Among these condensers, a so-called multi-layer ceramic condenser is a chip type condenser that includes multiple layers of dielectric sheets and electrodes as small thin films according to the use of the capacitance and the rated voltage. Since a surface mount technology can be used for the multi-layer ceramic condenser, the condenser can have high efficiency and high reliability. Further, since the chip type condenser has a small internal inductance, it can also be used in a high frequency band. The chip type condenser is widely used for a by-pass filter and an electronic device having, for example, an integro-differential circuit.
FIGS. 1A and 1B are vertical cross-sectional views illustrating a method of manufacturing a multi-layer ceramic condenser according to the related art. Referring to FIG. 1A, ceramic dielectric sheets 1a, 1b, 1c, and 1d are laminated to form a laminate 1. Specifically, glass-ceramic powder, a dielectric material, an organic binder, a dispersing agent, and a mixed solvent are mixed with each other to form slurry. The slurry is coated using a doctor blade method, and then dried, thereby manufacturing one ceramic dielectric sheet. By using this method, the plurality of ceramic dielectric sheets 1a, 1b, 1c, and 1d are manufactured, and then laminated. Here, before the ceramic dielectric sheets 1a, 1b, 1c, and 1d are laminated, conductive paste is applied to each of the ceramic dielectric sheets by screen printing to form internal electrodes 2 inside the laminate 1.
Then, a firing process is performed at a firing temperature of the laminate 1. Here, the firing temperature of the laminate 1 may be in the range of approximately 600 to 1000° C. The laminate 1 is sintered and shrunk during the firing process.
Then, the laminate 1 is cut along the line a-a′ and the line b-b′ so that the internal electrodes 12 are exposed to the outside. Conductive paste is applied to both side surfaces of the laminate 1 by using a dipping method or a wheel transfer method. The laminate 1 applied with the conductive paste is then re-heated, and dried to form external electrodes 3. As a result, a multi-layer ceramic condenser 10, shown in FIG. 1B, can be manufactured.
In the related art, according to the method of manufacturing the multi-layer ceramic condenser 10, the external electrodes 3 are formed after the laminate 1 is completely sintered during the firing process, which causes poor adhesion between the laminate 1 and the external electrodes 3. In general, the adhesion between the laminate 1 and the external electrodes 3 may be determined by the amount of glass components remaining in the laminate 1. However, since the glass components included in the laminate 1 are crystallized during the firing process, the amount of the glass components remaining in the laminate 1 is significantly reduced. Therefore, even though the re-heating process is performed after the conductive paste is applied to the laminate 1, the adhesion between the laminate 1 and the external electrodes 3 may be significantly reduced. Further, the re-heating process causes an increase in processing time and processing cost, thereby increasing an increase in product cost.